1. Field of the Invention
The invention relates to a terminal pin, and more particularly to a terminal pin which is pressed into a through hole in a printed circuit board (PCB).
2. Related Art
Terminal pins are used, for example, as a wrapping post around which is wound a wire. Such wrapping posts are shown in FIG. 4, wherein pin 1 made of conductive material has a compressed portion 2 which is pressed into a through hole 4 of a PCB 3, so that pin 1 is firmly fixed to the PCB 3. If the compressed portion 2 has a simple square cross section as illustrated in FIG. 4, the compressed portion 2 cannot be properly fitted into through hole 4 due to inaccurate dimensions of through hole 4. Further, only the four corners of portion 2 contact the circular surface of the hole, limiting the electrical contact.
Referring to FIG. 5a, compressed portion 2 has a slit 5 between side portions 2a and 2b which results in a cross section shown in FIG. 5b by applying plastic deformation to the compressed portion 2. According to this design the dimensional errors of through hole 4 can be compensated for by elastic deformation of compressed portion 2. However, the compressed portion 2, when inserted, has only two contact points against the circular side of through hole 4. Thus, the rigidness of the cross section is reduced, and compressed portion 2 is easily deformed when it is inserted into a through hole. In addition, the pin 1 is required to have a given dimension in thickness to mold the cross section mentioned above. Accordingly, the design shown in FIG. 5 is not applicable for a PCB with small through holes.
Other cross sections of compressed portions are shown in FIG. 6 and FIG. 7. In FIG. 6 compressed portion 2 has a V-shaped web 2c between a pair of flanges which, however, are subject to complicated processing during insertion, thereby resulting in wear of the flanges when pressed into through holes. The structure shown in FIG. 7 has a C-shaped cross section, which has no contacting point against through holes so that pin 1 is subject to rotation after insertion into a through hole when an external torque is applied thereon.